The basic structure of all filters is determined by the coefficient value extracted from each algorithm and by this tab number. Therefore, the FIR (Finite Impulse Response) filter with non-symmetric structure can be embodied when the above coefficient value and tab number are determined.
The below expression shows the relation between filter tab numbers and tab coefficients. EQU K=(M+1)/2, M is an odd number EQU K=M/2, M is an even number (1)
In the above, M means the tab number and K means the tab coefficient number.
For example, in the case of FIR (Finite Impulse Response) filter with 31 tabs of non-symmetric frequency response, the tab coefficient number is to be (31+1)/2=16. Input this into the filter to produce the desired value.
However, the prior FIR (Finite Impulse Response) filter like the above executes the arithmetic operation as much of tab number. It needs the same number of multipliers as that of the tabs; the size of the filter is supposed to get larger in proportion to the above tab numbers, which is the problem.
In other words, the main factor determining the chip size of IC (Integrated Circuit) is multiplier; there is a problem that the chip size is not to be diminished as this multiplier numbers increase in proportion to the tab numbers.